This invention was the subject matter of Document Disclosure Program Registration No. 511,426, filed in the U.S. Patent and Trademark Office on May 13, 2002.
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1. Field of the Invention
The present invention relates to the field of retractable blade protectors for cutting implements in general and in particular to a retractable wheelded guard for a box cutter or the like.
2. Description of Related Art
As can be seen by reference to the following U.S. Pat. Nos. 4,086,698; 4,987,682; 5,144,749, and 4,091,537, the prior art is replete with myriad and diverse safety gurad arrangements for utility knives, box cutters, or the like.
While all of the aforementioned prior art constructions are more than adequate for the basic purpose and function for which they have been specifically designed, they are uniformly deficient with respect to their failure to provide a simple, efficient, and practical retractable wheeled blade guard for utility knives.
As most users of utility knives are all too well aware particularly while cutting open a box or carton it is extremely difficult sometimes to control the depth of penetration of the box while making a sweeping cutting motion, and this difficulty sometimes results in the unintended damage to the contents of the box or carton.
As a consequence of the foregoing situation, there has existed a longstanding need among users of utility knives for a new and improved retractable blade guard that bboth limits the depth of penetration of the cutting blade, facilitates the movement of hte vutting blade along the top of a box or carton and immediately resumes its blade guard role at the end of the effective cutting motion, and the provision of such a construction is a stated objective of the present invention.
Briefly stated, the safety knife construction that forms the basis of the present invnetion comprises a conventional retractable blade utility knife to which is added a ounting member and a wheeled arm member that is pivotally connected to the mounting member and urged into a normally closed blade covering position by a spsring biasing element.
As will be explained in greater detail further on in the specification, the normally closed blade covering position of the wheeled arm member can be overcome by the user prior to initiating the cutting stroke by orienting the utility knife in a downward position such that the wheeled arm member can be foreced rearwardly agaisnt the opposing force of the spring biasing element.
Then once the wheel on the outboard end of the mounting member and the top of a box or carton the maximum depth of hte utility knife cutting blade will be established.
Also at the effective end of hte cutting stroke the spring biasing elemtn will immediately restore the wheeled arm member into its normally closed blade covering position.